Solid propellant catapult with liquid propellant rocket assist



May 15, 1962 A. M. sTOTT ET A1.

soLID PROPELLANT CATAPULI WITH LIQUID PROPELLANT ROCKET AssIs'r FiledDec. 4, 1958 rates asserts Patented May: 515;.Y 1962 i The inventiondescribed herein may be manufactured and used by or for the Governmentfor governmental purposes without the payment to us of any Y royaltythereon. l

This invention relates to catapults such as are utilized to eject a massfrom a moving aircraft, and more particularly to a catapult of the typewherein the application of one force to the mass is followed by theapplication of another force which continues to be exerted for some timeafter the mass has left the aircraft.

As stated in a copending application of Hugh D. Mac- Donald, Ir., AlbertM. Stott and Normal l. Waecker, Serial No. 727,750, tiled April 10, 1958for Extensible Rocket Catapult, it is desirable that the application ofthe ejecting force be continued for a timeV interval after the massleaves the aircraft. This has the advantage that it imparts a highertrajectory to the mass, minimizes its deceleration and stabilizes it sothat it does not tumble.

ln achieving these results, the invention off the aforesaid copendingapplication utilizes a solid propellant rocket. This operatessatisfactorily under -most conditions but leaves something to be desiredwhere therthruster is required to operate at very low temperatures.`This is so far the reason that the solid propellant is brittle at lowtemperatures and subject to failure through cracking and disintegrationbefore and during burning.

The present invention avoids this diiculty by the provision of animproved catapult which is similar to that of the aforesaid copendinglapplication in that the initial ejecting force is produced by a solidpropellant but differs therefrom in that the rocket propellant is aliquid which is ignited by a catalytic and/or pyrotechnic flame holderpreviously heated by the gas generated by the solid propellant.

The invention will be better understood from the following descriptionwhen considered in connection with the accompanying drawings and itsscope is indicated by the appended claims.

Referring to the drawings:

FIG. l is a sectional view of the catapult in its standby condition, and

FIG. 2 illustrates the removable part of the catapult, immediatelyfollowing its separation from the part remaining with the aircraft.

The figures of the drawing show a member lo which is attached to theaircraft and a member 11 which is attached to the mass to be ejected.

An inner tube 12 is threaded onto the member 10 at one end and hasextending into its other end a detachable plug 13. This plug haslongitudinal grooves 14 around its outer periphery and Iforms an annularrecess 15 which opens into the inner tube 12 through a plurality ofpassageways 16. The lands between the grooves 14 form a shoulder 48adapted to engage a shoulder 49 for a purpose hereinafter explained. Therecess 15 contains a ame holder 17 and, in its illustrated position,registers with openings 18 in the tube 12. The flame holder may consistof particles or mesh of platinum, zirconium or the like.

The inner tube 12 is coupled to a member 19 by a lock including twoU-shaped members 20 and 21 and a member`22 -which has its opposite endsin the formof pistons 23 and 24 and its intermediate section in the formof a tapered Wedge 25. Inthe illustrated positions ofthe various parts,the U-shaped members 2d and 21 are ixed in position by their engagementwtih the piston 24 and a shear pin 24a. When the member 22 is movedtoward the member 10, however, shear'pin 24a shears and the wedge 25moves the U-shaped members 20 and 21 toward one another so that theinner tube 12 is unlocked from the member 19. v

The member 19 (l) is attached to the outer casing 26'ot` a liquidchamber 27 by means of a thread 2S, (2) is attached to the inner casing29 of this chamber through a thread 3l), land (3) has extending throughit a plurality of orifices 31.

The outer casing 26 has a nozzle 32 threaded into one of its ends and atits other end is threaded onto an outwardly extending angeA 33 of a cap33b to which the position. Located adjacent these openings and betweenthe plug 13 and the end cap member 11 is an explosive cartridge 39 whichhas a casing 39A. The means for tiring this cartridge are illustrated asa firing pin 40 which is anchored to the member 11 by a shear pin 41 andactuated by a gas applied Vunder pressure through an inlet port 4Z.Obviously the cartridge may be tired electrically, mechanically or inany other conventional manner.

Seal rings are provided at points where parts are moved with'respect toone another. Thus the tiring pin 4@ has a seal ring 43, the piston 36has sealrings 44 and 45, the piston 23 has a seal ring' 46, and themember 19 has Aseal ring 47.

The gas generated by the -firingof the cartridge 39 j. produces fourefects after it ruptures'v'th'e.c'asing39A. It passes through openings37 and 38 causing the piston 36 to exert pressure on the liquidpropellant whereby the diaphragm 35 is ruptured. It passes through slots14 and openings '18 into recess 15 where it heats the ame holder 17. ltpasses through passageways 1.6 into the inner tube 12, driving thepiston 23 toward the member 10 and unlocking the member 19 from the tube12 which is fixed to the aircraft. It initiates the movement of thenozzle and liquid propellant chamber away from the aircraft.

This movement brings the member 19 into` engagement with the shouldersor lands extending between the slots 14 in the detachable plug 13 sothat the liquid propellant orices 311 now open into the flame holderrecess 15 where the highly heated platinum, or other material, ignitesthe liquid propellant. Further movement of the liquid chamber withdrawsthe plug 13 from the inner tube 12 which separates completely from thedevice. Under these conditions, the gas generated by the ring of theliquid propellant passes through the passageways 16 and around edge ofthe plug 13 and is discharged through the nozzle 32. Thereafter, theparts shown inV FIG. 2 are separated vfrom the inner y'tube and functionas a liquid propellant rocket, its fuel being forced out of the chamberby the pressure of the trapped gas acting on the piston 36 and ignitedby the flame holderr17. As explained in the aforesaid copendingapplication, the nozzle 32 is so adjusted and directed as to provide thedesired vertical and horizontal thrust.

We claim:

1. In a catapult having a lirst means for attaching it to a vehicle anda second means for attaching it to a mass to be moved from said vehicle,the combination of a tube closed at its downstream end by said firstmeans and fixed thereto, an annular chamber fixed to said second meansand encircling said tube, said annular chamber enclosing a liquidpropellant and havin7 a floating piston at its upstream end, arupturable diaphragm adjacent the downstream end of said liquidpropellant, a nozzle fixed to the downstream end of said annularchamber, an annular member fixed between said diaphragm and nozzle andhaving an interior shoulder perforated by passageways leading from saiddiaphragm through said shoulder, a plug detachably supported in theupstream end of said tube, means forming with the upper surface of saidplug, said second means and said annular chamber a combustion chamberopening into said annular chamber on the upstream side of said floatingpiston, said plug having an exterior shoulder alined with the interiorshoulder of said annular member and having an inner recess with aplurality of passageways leading from said combustion chamber throughsaid recess out the downstream end of said plug, a flame holder in saidrecess, means locking the downstream end or" said tube to said annularmember, and means for generating in said combustion chamber a gaspressure whereby said diaphragm is ruptured, said locking means isactuated to release said annular member from said tube, said annularchamber is moved to bring said recess into alinement with thepassageways of said annular member, and said interior and exteriorshoulders are engaged to strip said plug from said tube.

2. In a catapult having a first means for attaching it to a vehicle anda second means for attaching it to a mass to be moved from said vehicle,the combination of a hollow member closed at its downstream end by saidfirst means and fixed thereto, a container ixed to said second means andenclosing a liquid propellant, a oating piston at the upstream end ofsaid propellant, a rupturable diaphragm at the downstream end of saidpropeliant, a nozzle xed to the downstream end of said container, aperforated member fixed between said diaphragm and nozzle and having aninterior shoulder perforated lby passageways leading from said diaphragmthrough said interior shoulder, a closure detachably supported in theupstream end of said hollow member the upper surface of which forms withsaid second means and said liquid propellant container a combustionchamber opening into said liquid propellant container on the upstreamside or" said oating piston, said closure having an exterior shoulderalined with said interior shoulder and having an inner recess with aplurality of passageways leading rom said combustion chamber throughsaid recess out the downstream side of said closure, a fiame holder insaid recess, means locking the downstream end of said hollow member tosaid perforated member, and means for generating in said combustionchamber a gas pressure whereby said diaphragm is ruptured, said lockingmeans is actuated to release said perforated member from said hollowmember, said liquid propellant container is moved to bring said recessinto alinement with the passageways of said perforated member, and saidexterior and interior shoulders are engaged to strip said closure fromsaid hollow member.

3. In a catapult having a first means for attaching it to a vehicle anda second means for attaching it to a mass to be moved from said vehicle,the combination of a hollow member closed at its downstream end by saidfirst means and xed thereto, a liquid propellant container fixed to saidsecond means, a floating piston in said container, a rupturablediaphragm at the downstream end of said container, a nozzle fixed to thedownstreaml end of said container, a perforated member adjacent to saiddiaphragm and having perforations leading .from said diaphragm to theinterior of said perforated member, a closure detachably supported inthe upstream end of said hollow member, said second means and saidcontainer forming with said closure a combustion chamber opening intosaid liquid propellant container on the upstream side of said fioatingpiston, said closure having an inner recess with a passageway leadingfrom said combustion chamber out of the downstream side of said closure,a flame' holder in said recess, means interlocking said hollow memberand said container, and means for generating in said combustion chambera gas pressure whereby said diaphragm is ruptured, said interlockingmeans is actuated to release said container from said hollow member, andsaid container is moved to bring the passageways of said perforatedmember into alinement with said recess.

4. In a catapult having a first means for attaching it to a vehicle anda second means for attaching it to a mass to be moved from said vehicle,the combination of a hollow member closed at its downstream end by saidfirst means and fixed thereto, a perforated closure detachably fixed tothe upstream endv of saidA hollow member and having a recess from whichpassageways extend through the upstream and downstream ends of saidclosure, a liquid propellant container fixed to said second means andforming with said second means and said perforated closure a combustionchamber located above said perforated closure and opening into theupstream end of said container, a pressure rupturable closure near thedownstream end of said container, a nozzle fixed to the downstream endof said container, means forming an outlet from said rupturable closure,means locking said hollow member to said container, and means forgenerating in said com- -bustion chamber a gas pressure whereby saidlocking means is actuated to release said container from said hellowmember and said container is moved to aline said recess with said outletfrom said rupturable closure.

References Cited in the file of this patent UNITED STATES PATENTS2,552,181 Kleinhans May 3, 1951 2,671,312 Roy Mar. 9, 1954 2,799,988Larrecq et al. July 23, 1957 2,874,539 Fox Feb. 24, 1958 2,900,150 Hirtet al c Aug. 18, 1959 OTHER R EFERENCES Aviation Week (Human IFactors),vol. 65, No. 20, Nov. 12, 1956, pp. 71, 72, 74 and 77.

